| 摘要 |
PROBLEM TO BE SOLVED: To stably operate an injector without requiring excessively high voltage for injector control. SOLUTION: For the charging control of a piezostack 2A in the injector 4, where the piezostack 2A thrusts and drives a valve element 423 of a back pressure control part 4b for the relief of back pressure on a needle 421 via oil pressure in a displacement increasing chamber 413, a first charging period for lifting the valve element 23, followed by a second charging period after a charge stop period, permits piezostack voltage reduced by piezoelectric effect during the charge stop period to be recovered to a voltage value required for fully lifting the valve element for suppressing a peak voltage of the piezostack 2A which is reached during the first charging period.
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